@R: red;

html,
body {
  height: 100%;
  overflow: hidden;
  background-color: antiquewhite;

  #app {
    font-size: 20px;

    .test {
      color: @R;
      transition: color .3s;

      &:hover {
        color: darken(@R, 20%)
      }
    }
  }
}

.box{
  width: 200px;
  height: 200px;
  background: url('./assets/images/111.png');
  background-size: 100% 100%;
}